The effect of high temperature treatments on the early stages of crown gall tumorigenesis in sunflowers was investigated. Treatments of 32 C initiated at various times during the first ten days after infection had a similar effect on tumors induced by Agrobacterium tumefaciens strains B(6) and C58. Tumor growth was sensitive to 32 C until 60 to 72 hours after infection and was stimulated by 32 ...

Heterogeneous ice nuclei are necessary, and the common epiphytic ice nucleation active (INA) bacteria Pseudomonas syringae van Hall and Erwinia herbicola (Löhnis) Dye are sufficient to incite frost injury to sensitive plants at -5 degrees C. The ice nucleation activity of the bacteria occurs at the same temperatures at which frost injury to sensitive plants occurs in nature. Bacterial ice nucle...

Temperature-induced changes in the decay of the light-induced proton gradient of chloroplast thylakoids isolated from chilling-resistant and chilling-sensitive plants have been examined. In the presence of N-methylphenazonium methosulfate, the thylakoids isolated from chilling-resistant barley (cv. Kanby) and pea (cv. Alaska) and chilling-sensitive mung bean (cv. Berken) plants showed temperatu...

Much research has been conducted on the changes in gene expression of the model plant Arabidopsis to low-oxygen stress. Flooding results in a low oxygen environment in the root zone. However, there is ample evidence that tolerance to soil flooding is more than tolerance to low oxygen alone. In this study, we investigated the physiological response and differential expression of root-related tra...

The effect of temperature on Hill activity has been compared in chilling-sensitive and chilling-resistant plants. The Arrhenius activation energy (Ea) for the photoreduction of 2,6-dichlorophenolindophenol by chloroplasts isolated from two chilling-sensitive plants, mung bean (Vigna radiata L. var. Mungo) and maize (Zea mays L. cv. PX 616), increased at low temperatures, below 17 C for mung bea...

Ultraviolet-B (UV-B) radiation can have wide-ranging impacts on plants. UV-B exposure can decrease the rate of photosynthesis, alter pigment concentrations, and damage DNA, proteins, and lipids; however, not all species are equally sensitive. Lemna minor and Spirodela polyrhiza, two sympatric aquatic plants, were exposed to 5 or 11 days of artificial UV-B radiation for 6 hours per day, and moni...

Levels of non-protein thiols (mostly glutathione, GSH), ascorbic acid (AA), and activities of the enzymes ascorbate peroxidase (AP), glutathione reductase (GR) and GSH S-transferase (GST) were determined in cell-free leaf extracts of acifluorfen-resistant and -sensitive tobacco plants. These parameters were examined also in detached leaves of the above plants exposed to acifluorfen stress. In l...